Generally, a liquid pumping head has widely been used for dispensing a liquid or a cream out of a container (such as a bottle or a can, etc.). The conventional pumping head as shown in FIG. 1 comprises a container cap "A" fixed onto a container for liquid; when the nozzle head "B" is pushed down and released, the piston "C" will pump the liquid in the container up. As soon as the piston "C" is pushed down, the spring "D" will be pressed downward to produce a dynamic force. As soon as the nozzel head "B" is released, the spring "D" will push the piston "C" upward to pump a liquid in the container up and into the liquid accumulator "F" through a delivery tube E; when the nozzle head "B" is pushed down again, the liquid pressure in the liquid accumulator "F" will cause the ball valve "G" to close the inlet of the accumulator, and to force the liquid to flow upward and out of the nozzle head "B".
Generally, the aforesaid ball valve "G" is made of plastics, or metal, or other plastic materials to provide a check function; since most of the liquids are viscous products (such as creams, shampoos or detergents), such liquids tends to form a coating layer on the ball valve "G" upon flowing through the valve when this occurs, after the ball valve "G" is fallen upon the inlet of the liquid accumulator "F", the inlet would not be closed completely as a result of an insufficient pressure of the ball valve "G"; in that case, the liquid in the liquid accumulator "F", if not being exhausted, would leak into the container. After a period of time, the nozzle head "B" would have more less difficulty to pump out the liquid, unless the nozzle head is compressed several times, and that would cause an inconvenience to a user.